Transmission fluid temperature sensor
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Transmission fluid temperature sensor
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The fluid temperature sensor, which is fitted in the transmission casing, supplies the control module with information on the current fluid temperature.
The sensor is NTC type, i.e. the integral sensor resistance is inversely dependent on the temperature. This means that the resistance decreases as the temperature increases.
Through an integral 1 kohm resistor, the transmission control module measures the temperature of the transmission fluid by applying +5 V to the sensor from pin 6.
The sensor is grounded at grounding point G34S.
The control module uses the information on the temperature to calculate shifting points and engagement of the lock-up function.
Diagnostics
A fault in the temperature sensor can generate the following 3 diagnostic trouble codes:
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If the temperature increases or decreases too slowly during the first 15 minutes of driving, diagnostic trouble code P0711 will be generated.
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A short-circuit to ground for 5 minutes will generate diagnostic trouble code P1812.
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An open/short circuit to B+ for 15 minutes will generate diagnostic trouble code P1813.
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Adaptive shifting programs
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If the temperature rises to 150°C, Lock-Up will be engaged in 2nd gear. Engaging Lock-Up prevents slip in the torque converter, which makes the temperature drop.
The adaptive temperature program is disengaged if:
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SPORT or WINTER are selected
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The ignition is switched OFF
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CHECK GEARBOX lamp lights up
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The temperature has sunk to a level at which the adaptive shifting program is no longer needed.
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